Statistical PT-symmetric lasing in an optical fiber network

PT-symmetry in optics is a condition whereby the real and imaginary parts of the refractive index across a photonic structure are deliberately balanced. This balance can lead to a host of novel optical phenomena, such as unidirectional invisibility, loss-induced lasing, single-mode lasing from multimode resonators, and non-reciprocal effects in conjunction with nonlinearities. Because PT-symmetry has been thought of as fragile, experimental realizations to date have been usually restricted to on-chip micro-devices. Here, we demonstrate that certain features of PT-symmetry are sufficiently robust to survive the statistical fluctuations associated with a macroscopic optical cavity. We construct optical-fiber-based coupled-cavities in excess of a kilometer in length (the free spectral range is less than 0.8 fm) with balanced gain and loss in two sub-cavities and examine the lasing dynamics. In such a macroscopic system, fluctuations can lead to a cavity-detuning exceeding the free spectral range. Nevertheless, by varying the gain-loss contrast, we observe that both the lasing threshold and the growth of the laser power follow the predicted behavior of a stable PT-symmetric structure. Furthermore, a statistical symmetry-breaking point is observed upon varying the cavity loss. These findings indicate that PT-symmetry is a more robust optical phenomenon than previously expected, and points to potential applications in optical fiber networks and fiber lasers.Comment: Submitted to Nature Communications, Pages 1-19: Main manuscript; Pages 20-38: Supplementary material

Development of Asbestos - Free Brake Pad Using Bagasse

Development of asbestos-free brake pad using bagasse was investigated with a view to replace the use of asbestos whose dust is carcinogenic. The bagasse were sieve into sieve grades of 100, 150, 250, 350 and 710µm. the sieve bagasse was used in production of brake pad in ratio of 70%bagasse-30%resin using compression moulding. The properties examined are microstructure analysis, hardness, compressive strength, density, flame resistance, water and oil absorption. The microstructure reveals uniform distribution of resin in the bagasse. The results obtained showed that the finer the sieve size the better the properties. The results obtained in this work were compared with that of commercial brake pad (asbestos based) and optimum formulation laboratory brake pad Palm Kernel Shell based (PKS), the results are in close agreement. Hence bagasse can be used in production of asbestos-free brake pad

Effect of tannery effluents on seed germination and growth of two sunflower cultivars

The wastewater of a tannery in Multan, Pakistan, was alkaline with high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) values along with much higher concentrations of total settle able salts and suspended solids, sodium adsorption ratio and high amount of sodium having the water quality class C3S1. Effluent was examined for its chemical constituents and the effect of its various dilutions was examined in greenhouse on two newly recommended sunflower cultivars (FH-330 and FH- 245) during their whole growth period. Percentage of germination, chlorophyll, carbohydrates and protein contents of both the sunflower cultivars showed significant (p = 0.05) decreasing trend with increasing effluent concentrations. Vegetative growth parameters like plant height and number of leaves per plant were significantly (p = 0.05) reduced with the increasing levels of effluents. Rate of leaf senescence of both cultivars was higher under higher effluent concentrations. Yield of sunflower crop in both cultivars was significantly (p = 0.05) reduced due to effluent concentrations. Seeds per capitulum were decreased to 49%, seeds weight per plant to 61 - 66% and 100-seed weight to 49 - 59%. The appearance of pale yellowish color of the affected plants was due to reduction in photosynthetic material under higher effluent concentration. Full strength effluent concentration caused the reduction in biomass accumulation and reproductive growth of sunflower cultivars. The results revealed that cultivar FH-330 was relatively resistant to varying effluent concentrations as compared to the cultivar FH- 245. However, the tannery effluents due to the presence of chemicals are not suitable for inclusion in irrigation system.Key words: Tannery effluents, sunflower, seed germination, growth, adverse effect, reduced yield

Response to the meningococcal meningitis epidemic (MME)at Aminu Kano Teaching Hospital, Kano (2008-2009)

No Abstract

Prevalence of hepatitis B and C and assessment of responsible risk factors among the vulnerable β-thalassemic patients of Azad Kashmir, Pakistan

Approximately 350 million patients of hepatitis B and 170 million patients of Hepatitis C are present worldwide according to WHO. Many risk factors are involved in the transmission of theses deadly viral infections but blood transfusion in Beta thalassemic patients is working with two faces, one as remedy and the other is key risk factor in the spread of silent killers. Thalassemia patients registered in Combine Military Hospital (CMH) Rawalakot and Sheikh Khalifa Bin Zayed Al-Nahyan Hospital, Muzaffarabad Azad Jammu and Kashmir Pakistan were studied for the viral hepatitis B and C prevalence. A total of 303 (including 164 males and 139 females) individuals, aged between 1 and 12 years were studied. All the understudy participants were interviewed through questionnaire method. After taking written consent from each participant or guardian, 5 ml of blood was collected from each participant and brought to the working laboratory for HBV and HCV screening through ICT kit method. All ICT positive samples were further confirmed through ELISA. Individuals 25(8.2%) were found positive for both hepatitis B surface Antigen (HBsAg) and Anti hepatitis C antibody (Anti-HCV antibody) after initial screening with no coinfection of both diseases. Out of 25 total infected individuals, 05(1.6%) were found HBsAg positive and 20(6.6%) were found anti-HCV positive. All the ICT positive individuals were further confirmed by quantitative Enzyme Linked Immunosorbent Assay (ELISA) and 23(7.6%) individuals were confirmed for both hepatitis B and C including 05(1.6%) HBsAg positive as well as 18(5.9%) anti-HCV antibody positive individuals. We can conclude that 8.2% prevalence of hepatitis B and C among thalassemic patients is an alarming health concern which directly indicates to pay attention for ensuring 100% safe blood transfusion

The electrokinetic impact on heavy metals remediation of Tasik Chini iron ore mine tailings, at Pahang state, Peninsular Malaysia

The improper disposal of mining tailings is a severe threat to the surrounding environment because it comprises high concentrations of heavy metals contamination. Any precious metal extraction (mining) produces millions of tons of waste; iron ore extraction is common globally, unlike other metals extraction. The iron ore tailings contain heavy metals such as Arsenic (As), Cobalt (Co), Manganese (Mn), Lead (Pb), Copper (Cu), and Zinc (Zn). This study focuses on extracting hazardous metals such as As, V, and Zn from the disposed waste and improving its geotechnical properties. Nine samples were collected from Tasik Chini Iron ore mine, Pekan district, Pahang State, Malaysia. The initial data were prepared for elemental analysis by following ICP-OES analysis. The results showed that As, Co, Mn, Pb, Cu, and Zn concentrations exceeded the standard guidelines. In recent years, sustainable remediations techniques (EKR) have attracted extensive attention, including the electrokinetic remediation technique. The (EKR) method was applied to extract these metals from iron ore tailings specimens. A comprehensive approach of EKR shows an outstanding result where the highest removal efficiency of As was 68.4 %, Co 64.5%, Mn 67.8%, Pb 67.1%, and Cu was 64.1% and Zn 64.9% with the voltage gradient of 100 and 150 V for 4 and 8 hours constantly. Increasing the voltage gradient could be a cost-effective long-term solution for the remediation of iron ore tailings. The existing method was experienced as an effective and green technique for extracting heavy metals and recycling the mining waste materials

Conserved Quantities in Noncommutative Principal Chiral Model with Wess-Zumino Term

We construct noncommutative extension of U(N) principal chiral model with Wess-Zumino term and obtain an infinite set of local and non-local conserved quantities for the model using iterative procedure of Brezin {\it et.al} \cite{BIZZ}. We also present the equivalent description as Lax formalism of the model. We expand the fields perturbatively and derive zeroth- and first-order equations of motion, zero-curvature condition, iteration method, Lax formalism, local and non-local conserved quantities.Comment: 14 Page

Calibrated cycles and T-duality

For Hitchin's generalised geometries we introduce and analyse the concept of a structured submanifold which encapsulates the classical notion of a calibrated submanifold. Under a suitable integrability condition on the ambient geometry, these generalised calibrated cycles minimise a functional occurring as D-brane energy in type II string theories, involving both so-called NS-NS- and R-R-fields. Further, we investigate the behaviour of calibrated cycles under T-duality and construct non-trivial examples.Comment: 43 pages. v4: formalism and T-duality part considerably expande

Availability and Co-Substrate Potential of Typha latifolia for Biogas Production in Funtua, Katsina State, Nigeria

In order to reduce global warming through fossil fuel utilization, biogas production from biodegradable biomass seems a sustainable alternative. This study evaluated the availability and co-substrate potential of T. latifolia for biogas production in Funtua, Katsina State Nigeria. A purposive sampling technique was used in selecting the wards that were used for this study. A 1204 metres transect was used for 32 quadrats; 19 of these were laid on the 953m contiguous land area at intervals of 50m; 9 quadrats covered 450m, 5 quadrats were on 250m, 3 on 153m, and 2 on 100m. The remaining 13 transects were laid on the 251m un-contiguous patches. Coordinates of various potentials sites were recorded using Global positioning system. There were an average of 27 T. latifolia stands per m2. A total of 32,388 of T. latifolia stands were recorded in the study area; Dukke ward (23,968), Makera (8,205) and Maska 216. T. latifolia is available in lqrge quantities, and a potential co substrate in anaerobic digestion for biogas production in Funtua. It is recommended that the study should be replicated in time later to establish a trend of the T. latifolia species in terms of population